There was some discussion as to whether the purple 'Hibotan' or "Moon Cactus" could survive on roots of it's own, as purple pigmentation doesn't mean a lack of chlorophyll, whereas the yellows, reds, and pinks are completely lacking any chlorophyll through a mutation. They therefore have to be grated to stock that does produce chlorophyll to survive, but what about the purple one?
I found a purple "Moon Cactus" in Home Depot after my G. mihanovichii var friedrichii succumbed to rot this summer (sigh, was my favorite one, almost gave up cactus growing for a minute there, but have since learned to alter my potting media and watering in this environment,) because this was as good a time as any to give it a shot. I removed the cactus and threw out the graft Hylocereus, let the Gymnocalycium's base heal and dry over for a few weeks. Then I just nestled it gently into some soil mix and let it sit for a while in some bright shade. I lightly watered the soil about once a month as the humidity was pretty high. Sure enough, the little cactus is now firmly rooted into the soil. Now it's trying to bloom.
So now I've got a small Gymnocalycium mihanovivhii var. friedrichii 'Hibotan'.....ha, can it's name get longer? The stalk and outer part of the flower is almost a violent shade of pink, more neon than a standard G. mihanovichii var. friedrichii. It's a little on the dehydrated side from having to make roots from a scarred over base, so now that it's settled in, maybe next year it'll grow some and flower better.
I felt a little bad for throwing out the Hylocereus base this cactus was growing on, but I already have a Hylocereus 'Halley's Comet' which is getting outrageously big. Then I was grocery shopping and guess what I found for sale....
Dragon fruit! Yup, this is the fruit of the Hylocereus undatus base plant that I threw out. Had I let it live on and flower, I'd get something similar fruit wise out of it. I love growing cacti from seed, so I was tempted to grow some of these seeds, but I don't have the space for them! Also, speaking of space, if anyone in the US is interested in a small cutting of my Hylocereus undatus x polyrhizus 'Halley's Comet', email me, I'll send you a piece for cost of shipping. They root easily from cuttings.